Continuity 47 



respect to Ether is meaningless: and the 

 fact that only relative motion of pieces 

 of matter with respect to each other has 

 so far been observed is the foundation of 

 the Principle of Relativity. It sounds 

 simple enough as thus stated, but in its 

 developments it is an ingenious and com- 

 plicated doctrine embodying surprising 

 consequences which have been worked 

 out by Professor Einstein and his disciples 

 with consummate ingenuity. 



What have I to urge against it? Well, 

 in the first place, it is only in accordance 

 with common sense that no effect of 

 the first order can be observed with- 

 out relative motion of matter. An 

 Ether-stream through our laboratories is 

 optically and electrically undetectable, 

 at least as regards first-order observa- 

 tion; this is clearly explained for general 

 readers in my book The Ether of 

 Space, Chapter TV. But the Principle of 

 Relativity says more than that, it says 

 that no effect of any order of magnitude 

 can ever be observed, without the rela- 

 tive motion of matter. 



